Interface-induced morphology transition in triblock copolymer films swollen with low-molecular-weight homopolymer.
The morphology transition due to midblock swelling with low-molecular-weight homopolymer polystyrene of an ABA-type triblock copolymer polyparamethylstyrene-block-polystyrene-block-polyparamethylstyrene at the buried silicon substrate interface is studied as a function of different substrate surface treatments. With grazing incidence small-angle neutron scattering (GISANS), high interface sensitivity is reached. The powderlike oriented lamellar structure in the bulk becomes oriented along the surface normal in the vicinity of the substrate. A transition of the lamellar into a cylinder phase at the polymer-silicon interface is probed with GISANS. The transition is induced by the addition of the homopolymer, but the modification of the short-ranged interface potential of the substrate influences the amount of homopolymer that is necessary for this transition. Without and with 0.1 vol % added homopolymer, the lateral spacing is stretched at the interface as compared to the bulk whereas for a higher added amount of homopolymer no stretching occurs.
Müller-Buschbaum
P
P
Technische Universität München, Physikdepartment E13, James-Franck-Strasse 1, 85747 Garching, Germany. muellerb@ph.tum.de
Schulz
L
L
Metwalli
E
E
Moulin
J F
JF
Cubitt
R
R